How weight loss surgery is performed

The three most widely used types of weight loss surgery are gastric banding and sleeve gastrectomy, both based on restriction, and gastric bypass, which uses a combination of restriction and malabsorption.

These operations are usually performed as a type of laparoscopic (keyhole) surgery, where a series of small incisions are made in the abdomen, rather than one large incision. The advantage of this type of surgery is it causes less pain afterwards and has a faster recovery time.

However, laparoscopic surgery may not always be possible in severely morbidly obese people, or those who have had other abdominal operations.

They are carried out under general anaesthetic, which means you'll be asleep during surgery and won't feel any pain.

The surgeon makes the incisions in your abdomen, then inserts an instrument known as a laparoscope through one of the cuts. A laparoscope is a thin, rigid tube containing a light source and a camera. The camera relays images of the inside of your abdomen to a television monitor.

Gastric banding

Other small instruments are placed through the cuts to place a gastric band around the top of your stomach, effectively dividing your stomach into two, leaving a small pouch at the top.

As it takes less food to fill the pouch, it takes less food to make you feel full.

The band is connected to an access port, which is placed under the skin. Saline (sterile salt water) can be passed through this port to inflate the band. This allows the band to be adjusted as required after surgery.

The surgery usually takes around an hour to complete.

Gastric bypass

Gastric bypass uses special surgical staplers to create a small pouch at the top of your stomach. This pouch is then connected directly to a section of your small intestine, bypassing the rest of the stomach and bowel.

This means it takes less food to make you feel full and you'll also absorb fewer calories from the food you eat.

Sleeve gastrectomy

During a sleeve gastrectomy, part of the stomach is removed. This restricts the amount of food that can be eaten and results in you feeling full sooner than normal when eating.

Bypass, banding or sleeve?

All three types of surgery have advantages and disadvantages.

There's usually more weight loss after a gastric bypass and sleeve gastrectomy than after a gastric band.

Most people with a gastric band lose around half their excess body weight, whereas most people with a gastric bypass or sleeve gastrectomy lose around two-thirds of their excess body weight.

However, because it's more technically demanding, a gastric bypass carries a higher risk of complications, including death. Read about the risks of weight loss surgery.

A gastric band is reversible, so if you find it difficult to cope with the restrictions associated with life after surgery, you can have the band removed.

A gastric bypass or a sleeve gastrectomy, on the other hand, can't be reversed. You'll also be required to take nutritional supplements for the rest of your life if you have a gastric bypass.

A gastric bypass often has a much greater impact on type 2 diabetes, in a shorter time, than either a gastric band or sleeve gastrectomy.

Discuss the advantages and disadvantages of both types of surgery with your surgical team.

Other types of bariatric surgery

Other types of weight loss surgery, which are less commonly used, are outlined below.

Bilo-pancreatic diversion

A bilo-pancreatic diversion is similar to a gastric bypass, except a much larger section of the small intestine is bypassed, meaning you'll absorb even fewer calories from the food you eat.

A bilo-pancreatic diversion can achieve a good level of weight loss (up to 80% of excess body weight) but it carries a high risk of complications and can cause unpleasant side effects, such as unpleasant-smelling diarrhoea.

Because of this, a bilo-pancreatic diversion is usually only recommended when it's felt that rapid weight loss is required to prevent a serious health condition, such as heart disease, from getting worse.

Intra-gastric balloon

An intra-gastric balloon is a soft silicone balloon that's surgically implanted into your stomach. The balloon is filled with air or saline solution (sterile salt water), and so takes up some of the space in your stomach. This means you don't need to eat as much before you feel full.

This procedure is only temporary, and the balloon is usually removed after six months. The procedure is useful if you don't meet the criteria for the other types of surgery – for example, because you're too obese.

An intra-gastric balloon procedure can usually be done without making an incision in your abdomen. Instead, the balloon can be passed through your mouth and down into your stomach using an endoscope (a thin, flexible tube that has a light and a camera on one end).